Manufacture of tin plate



S. A. DAVIS MANUFACTURE OF TIN PLATE v Filed June 25, 1919 5 Sheets-Sheet l INVENTOR z gig: I

Mar. 3, 1925.

s. A. DAVIS MANUFACTURE OF TIN PLATE Filed June 25, 1919 5 Sheets-Sheet 2 ns. g

INVENTOR 5. A. DAVIS Fil ed June 25; 1919 3 Sheets-Sheet 5 iii f:

FIG. 3

INVENTOR v AA/ZJW Patented Mar. "3, 19 25- umriio .S T-ATESL.

"PATENT OFFICE. 1'"

s'rnwm A. paws, i'o r same: man ream 'IIOH- or Nnw munc'runa or rm rm'rn.

Application fled June as, 1919. 8erla11l'o. 306,521.

To all whom it my camera:

Be itknown tha- .I', STEWART -.A. DAvrs, of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in the Manufacture of Tin Plate, of which the following is a specification.

My invention relates generally to the 'ma-nufacture of tin plate. The invention 10 more particularly relates to the manufacture of that cheaper grade of tin plate having a relatively thin-"or lightweight coating 'of tinknown commercially as coke plate. Tin late is sold. universally by the base box, a ase box being the equivalent of 112 plates, 14 inches by inches by-3O gage, 011 f totalling 31360 square inches .superficia rea. p

The standard'commercial grade of coke 20 plate carries approximately one and onehalf pounds of tin per base box, is without a high lustre, and is dull or dry in appearance. The coating on commercial coke plate is not entirely continuous, but contains small openings or channels running coating to the 'ferroussheet underneath-and formif what is technically known as pin holesi.""iAs the thickness of the tin coating is increased on commercial coke-plate its lustre is improved, approximately in proportion as the weight-of tin per base box in creases. The number of pin holes, however,

do not decreasezinithis same proportion. Thus a coke plate carryin two pounds of tin per base box has a distinctly higher lustre than a plate coated with one and one-half pounds, although the number of pin holespe'r' unit of area is not materially changed. y

The processof manufacturing tin plate, as carried .onheretofore, consists essentially in passing the cleaned iron or steel plate or base, by hand, through a layer of flux into a bath of molten tin, subsequently withdrawin the plate and removing the surplus ad ering tin from the surface by means of rotary, spring pressed sets of exit rolls. When the ferrous base and moltentin first come into cont ct, a layer of an iron-tin 9 alloy forms on the surfaces of the base,

this alloy having'a melting point higher than that of the molten tin itself. The result of this action is "that fine needle-like crystals of this iron-tin all'oy' are formed The through the- "pot, which are located within a body of palm oil, the network of crystals is crushed and flattened against the iron base, and a large portion 0 'the molten, interstitial tin is squeezed out'and flows oil' the plate. The body of molten tin within the pot in reality soon becomes a saturated solution of iron-tin alloy in molten tin, this being shown by the large amount of, scrufl' or iron-tin alloyl which becomes deposited on the bottom e pot, in the oil or exit end of the pot. plate, as it emerges from between the exit r0 ls, therefore, consists of the ferrous base covered with a coating which is'composed of "a mixture of the crystals of iron tin alloy audpure tin.' The presence of the crystals produces what can be seen under a microscope to be a rough irregular surface, which in turnimparts the dull or as technically termed, the dry appearance bf the surfaces of the coke plate.

In car ing'out the old princess great care is taken to ee the yield at or below a cer:

tain limit, t e-yield varying with diiferent rades of tin plate and being determined y the particular grade of tin plate being.

The yield has been controlled by re ulating the speed at which the plates aremade.

fe out of the tin-pot, the general practice being to reduce the speed of feeding'the plates through the tinning machine (within certain-limits) to lessen the yield. This was done because experience had shown an increase in the speed of passing the plates through the tinnin bath was followed by an increase in yiel A speed offrom 100 to 120 inches per minute has been considered the maximum possible in making coke plate. It also is a matter of eneral knowledge that keeping the plates within the bath of molten tin for'too" long time interval results. in making plates having black spots (i. e. spots wherethe tin does not adhere to the-base).

The primary object of my invention is the provision of a novel method of applying the coatin of tin to the iron or steel plates whereby e speedat which the tinning operation is effected can be very materially increased without undue increase in ,the yield, (a trade term denoting the amount of tin'used in coating per unit of area of the coated surfaces,) and whereby the capacity of the tinning machines is greatly increased and the cost ofma-king tin plate correspondingly lessened.

Another object of the invention is to provide'lan improved method of tinning ferrous metal plates whereby, without increase in the yield, a product is obtained having the Veryhigh lustre characteristic of the heavi-' ly coated, high grade tin plate, such as charcoal, plate, and the absenceof pin holes characteristic of both coke and charcoal grades as heretofore made by the old process.

,Another object of theinvention is to provide an improved method of making coke plate whereby the yield or weight of tin per unit of area ofthe coke .plate may be materially reduced, and an'cnormous saving in the amount of tin used is therebyeifected,

and other imperfections present when made by the old'process are lessened and overs come.

Referring now to the drawings forming part of this specification, Figure l is a plan showing a tinning pot constructed and ar-' ranged in accordance with this invention.

' FIgUIG 2' is a longitudinal section, on the line IIII of Figure 1, showing a preferred "arrangement of apparatus embodying the invention and adapted for use in carrying out the method forming part of my invention.-

Fi ure 3. is a sectional end elevation, on the line IIIIII of Figure 2, showing further details in the construction and arrangement of the apparatus.

Figure 4 is a plan, and Figure 5 is a side elevation showing details in the construction of the roll and feed roller driving mechanism forming part of my improved tinning machine.

In the accompanying drawings, the letter A designates a tinning pot, in itself an old and approved form. The pot is separated transversely by a vertical wall or partition.-

2 into compartments Band C. Y The lower edge of this septum 2, which terminates above the bottom of the tinning pot, and the upper ed e of a rib or projection 3 on the bottom 0 the pot defines thewidth or vertical dimensions of a narrow passage or Yment C ofthe pot A. The particular pot shown is of a width which permits of two ,-or more plates, side by side, being passed through the tinning pot. (See Figures 1 and '3.) Obviously, when desired, a narrower pot of a width slightly greater than the width of the widest plate may be used. Any of several known means may be provided for heating the tinning pot and preferably these means will be constructed and arranged 'to maintain the tin in the compartment B at a considerably higher temperature than the molten tinvin the compartment 0.

The heating apparatus, not forming part of this invention, isnot shown nor further described.

wardl'y so that this compartment is conside-rably deeper than the other compartment B, this old and well known constructioncnablinga body of oil, generally palm oil, of

the requisite depth or, thickness, to be maintained'on topof the moltentin in the compartment G. The levels'at-which the bath I of molten tin is maintained in the pot are indicated by tlie line XX of Figure 2, and a thinlayer H of flux, such as zinc chloride, is maintained on top of the tin in the compartment B on the entrance end of the pot. It is due to the weight of this The side walls of the compartment at the exit end of the pot are extended up-.

'body of oil that the level of the tin bath in the compartment G is somewhat lower than that of the molten bath in the compartment B. The upper level at which the oil is maintained in the compartment C is indicated by the line ZZ.

Located immediately above the upper edge of the compartment B, at the-plate entering side of the tinning pot, are two sets of spring pressed feed rollers E and F, which are arranged to move the pickled and washed plates forwardly and downwardly into the tin-pot at an angle to the horizontal. The rollers 6 and 7 forming the set F are at a somewhat lower level than the rollers 4 and 5 of the set E. An adjustable roller G, located on the discharge side of the set F, is provided to guide and direct the front end of the successive plates forwardly and downwardlythrough the layer of flux H into the molten tin in compartment B, as they emerge from between the rollers of the set F.

Positioned within the compartment 1 B,

' closely adjacent to the passage u, 15 a set of the compartment B into the compartment 0 enterthe molten tin in compartment B of 2 operation by 10 part of my invention, as will be more fully explained hereinafter.

the tin-pot. This flattening and smoothing the rolls 8 and 9 of the set I is 4 novel, and forms a vital and very important t should be noted that the sets of feedin rollers E and Fund "the'vuide roller G- are above the layer of flux and that the successive plates are mechanically fed and guided into the tinning pot.

The location of the pressure rolls I with respect to the layer of. flux H also shouldbe. noted. It has heretofore been considered im possible to use submerged feed-out rollers in a tinning machine. This is because exper-ience shows th t long contactof the rolls with the molten tin bath causes the layer of tin on the rollers to flake off and bare the surface of the rollers, and that when this occurs the result is the making of defec-v tively coated plates, known in the artas having' black spots i. e.-plates' having. unco'ated spots on the surfaces thereof.

But by positioning the p-ressurerollsI so that the distance from the flux H is not too great, sufficient flux is carried down by the plates to maintain the rolls I in working condition.

Two sets-of feed-out rollers J and K are provided wh ch are located Within thebody of oil maintained on .top of the tin in the compartment C of the pot A. The sets of. rollers J and K are arranged-to not only feed theplates 'outof thetinpot, but also act toly out of the tinning pot.

squeeze ofl' surplus tin from the smooth alloy coated surfaces ofthe plates assing upward- The body of oil in which these rollers are submerged acts to prevent the molten coating on the surfaces of the plates from contacting-with the atmosphere, until after the excess coating has been removed therefrom.

An inclined apron plate 14 is provided at the entrance end of the-compartmentB of the pot to receive the plates as delivered toy the tinning pot. Plates 15 and 16 forma the set F. T

"ment B so as. to

guide L for directing the. front end of the successive plates as they merge..from-between the set of rollers E into the bite of Curved guide plates 1 and lg'forming a guide M are positioned within thecompartdirect the forward ,end' of the plates being tinned into the nipof the in Figure 2. These set I of pressure rolls, as is clearly shdwnguide plates 17, 18, preferably, are made of skeleton form so as to not interfere with the settling of scrufl and pairs to the feed-in apparatus.

any foreign material. in the molten tin to 4 the.bottom'of the compartment B 'of the -.lower set-J of two sets "of" feed-outrollers J and Kflwithin theuppe'r end of the comparts ment Onof the tin-pot. It will be seen by reference to Figure 2 that the rear end of the curved lowermost guide plate 20 extends backwardly through the, passage D into proximity to the set of rolls I. 4

The'frame work 0, which supports the. setsof feed rollers E and F, guide roller G and pressure rolls I and the stationary uides L and M, is removably secured withm the compartment B so as to ermit' of the feed-in apparatus to be removed bodily from the. pot while the tin bath is molten. This, is. one at intervals in order to clean the tinning pot, and when necessary to make refeed out rollers J and K and guide N are similarly mounted on a frame work P in the compartment C of the pot, and are taken out of and replaced in the compartment G in the same manner as the apparatus within the; other compartment B.

The feed rollers 4 and 5 of the set E are connected together by pairs of spur gears 21 to positively drive these rollers atthe same The sets of surface speed, and the rollers 6 and 7 of the set F have meshing spur gears 22- on one end for a sim' also have meshing spur gears 23 on one end to positively rotate these rolls.

The pairs of feed-outrolls forming the sets J and K in the compartment C of the tinning" pot also are geared together by spur gears 24 to positively rotate the pair of rolls forming each set. I

The rolls 8 of the, pressure rolls and the rollers 6 and a of thesets of'feed-in rollers F and E are connected together by bevel gears 25, one gear of each pair being keyed on, the shaft 26 and this shaft being rotatably secured in bearings 27 mounted on an'anglesup ort 28 which is fastened on one side of the rainefworkOdn the compartli a f h f d spur- 1'29/011 een o te ee roller t mesfifz g with a similar 'gear 30 on the stub shaft 31 and this stub. shaft hasa 1lar purpose. The'rolls 8 and 9 sprocket'wheel 32 on one end which is driven 4 a sprocket chainfrom-a suitable motor ,(not shown). I c The rollers formingthe-sets of feed-out rollers J and K arepositively driven. in the usual and wellknown-manner. 1

Incarrying outm'y improved process with- -a tinningmachine constructed essentially as shown and described. the plate sheet of iron or steel, afterbeingypickled and washed, is placed on the apron let and vis moved downwardly thereon until its frontend enters the nip of the, set E of feed rollers. The plate, upon emerging from between these rollersipasses through the "guide L into the nip [0 the second pair F' -of feed rollers, which are located imme'diately above the layer 0t flux H in the flux box.

The plates as supplied to the apron let from the washing bath have some water adhering to them. The wet plates in passin through the feed rollers E and'F are freed from substantially, all water," the; small amount'rem-aiiiing acting to maintain the 4 flux in a suitable condition. With the displacement ofthis excess water there also is removed lr'om the plates certain foreign materials which frequently adhere thereto' a In passing from between therollers ,F, the 'plate' is digected into the flux H by the adjustable gui e roller (disc that the plate at no time comes .intocontact with any ex-v tension or guide projecting below or beyond the level of the flux. This provision of means'for entering the sheets into the tin through theflux'without having the plates come 1n contact with any stationary [part of the pot avoids the dislodgement of con-- gealed flux and. other substances which have previously been deposited and which .would otherwise be carried into the molten tin bath. The rapid downward movement of the sheet through the flux into the tin bath and 'be-' tween the pressure rolls I carries 'sufiicient flux to these Submerged rolls to maintain them in proper workin condition.

After passing throng the flux, the plate enters the molten tin in the compartment B, passing thro'ugh'the curved guide M. This guide is preferably of skeletonconstruction as shown, so as'to permit the deposition of scrufi' or other foreign materials on the bottom of the compartment. B. The guide M discharges the plates into the nip of the rolls I which set of pressure and .cleanin are preferably made from so 1d steel and are ground and olish'ed. The rolls'I obviously,

will be provi-ded'with a-suitable mechanism for regulating the pressure on the plates passing between them, and as has been stated, will be. driven by a mechanism which provides a uniform Jlineal speed for the sheet as it passes through the pot.

In passing the plates between the pres? sure rolls I,' the porous mass of needle-like crystals of iron-tin alloy formed on the plate as it passes into the molten-tin .bath, is

,rolled down-and flattened and s 'noothed,

and the surplus; interstitial tin, which is still molten is squeezed, out and removed from the alloy coating now on the plate. Some tin alloy coating also is removed, as

is shown by the deposit of scrufl which 001- lects on the bottom of the pot below these rolls. From the rolls I, the plate, now havand thence between the secondset 'K-i 1 ing a flattened-and smoothed iron-tin alloy coating, passes-through the opening 1) and -is deflected by the curved guide N int the nip of the first'pairoffeed-out rollers out of the tinnin" p .1,

j The iron-tin a oy, formed asa porous,

the iron sheet,v when the plate enters the on bath, 'is flattened out and. pressed closely upon the plate by the rolls I. There being but little agitation of the molten metal in the pot, the-flattening and. smoothing ope'ration and the removal of the eXce'ssiron-tin alloy while the plate is in the compartment .13 and "before reaching the compartment C of the. tin-pot, the tin in the compartment -"C remains substantially pure and does'not' become saturated with iron-tin alloyas with the old methods; Any excess alloy not tightlyadhering to the sheet also is removed and is forced into the tin bath; ally settling to the bottom of -the pot directly-below t e rolls. This disposition of the rolls I rela We to theslot or passage D in the pot prevents contamination of the tin on the spongy vnet-work of very fine'crystals upon oil side of thes'lot by the accumulated scrufl' or alloy and other impurities which, in the present case, collect in the pot in the flux side of the passage D and become deposited in the compartment B. a a

excess tin adhering to the smoothed A12 and attened iron-tin alloy on the plates is v removedby the pressure (if-the sets of feedoutrollersJ and K, and -a finished coke Another advantage is that instead of feed-' ing the plates through the pot at a speed of not exceeding about 120 inches per minute, they can travel at a ratcjup to 200- or more niches per minute, and llllS'1I1-' creased speed-results-m an enormous increase in thejcapacity of the tinning pots,

while the action of the pressure rollsresults in a large saving in theamount of-tin used for coating theplates. 'The increased speed of tinning and reduction in yield is made plate is provided havin an outer layer. of liich has the lustre possible through the removal of excess tin from the interstices of the spongy, porous layer -ofiron-tin alloy. (WhlCh is formed on the plates as theyienter the bath of molten tin), by the considerable pressure exerted by the pressure rolls and the flattening and smoothing of the alloy layer, at a time early tenedand smoothed coating of alloy to acquire a second coating of substantially pure ltd tin and early enough for a'nyexcess tin to be wiped off or removedfrom the alloy coating by the action of the feed-out rollers,- instead of-having the spongy, .porous alloy layer acted upon only by the feed-out rollers, as is the case in the methods used heretofore. A further advantage is'in the production of 'a superior coke plate hav-ing'the finish or lustre of the heavily coated fcharcoal'plates and having a lighter-coating of tin than is possible With any known processor apparatus heretofore used in making coke or other tin plate.

Modifications in the construction and ar- :rangement of the apparatus used in carrying- .out the method forming'part of this invention maybe made vvithout departing from the inventionjas defined in the appendedclaims.

I claim: i i 1. In the manufacture of tin; plate, the successive steps consisting in introducing the plates successively through a flux into and through a .bath of molten tin and through an oil bath, in the passage thereof out of the molten tin, subjecting the lates to roller pressure while submerged in t 1e tin bath, tosthereby smooth and flatten the coating and remove excess tin, and again subjecting the plates to roller pressure in the passage thereof through the oil bath tore move surplus tin remaining on the coated sheets, and successively-feedingthe plates at a uniform speed of at least 150 inches per minute into, through and out of the flu'x,.the tin bath and the oil bath.

.2. In the manufacture of tin plate, the step consistin of feeding the plates introduced into t e tin pot successively into, through, and out'of the flux, the tin bath and the oil bath at a uniformspeed of'not less than 120 inches per minute.

3. In the manufacture 'of' tin plate,tthe

I step consisting of feeding the plates introduced into the tin potsuccessively into, through, and out of the flux, the tin bath and the oil bath, at a uniform speed of at least 150 inches per minute.

at. In the manufacture of tin plate, the

steps consisting of introducing the plates into thetin pot, passing eachplate into and through the flux'into the ,molten tin bath and into and through the oil bath from the tin bath, squeezing the coated late, to remove surplus molten tin there rom, in its passage through the oil'bath, and 'feedin eachi'plate successively into andthrough an out of-the flux, the tin bath. and the oil bath than 120.inches per minute.

5. In the manufacture of tin steps consisting of introducin t into the tin pot, passing each pIate late to remove surplus molten t-in there-.

rom; in the. passage of 'the coated plate through the oil bath, and feeding each plate successively into and through and out of the flux, the. tinbath and the oil bath, at a substantially constant speed of at least 150 inches per minute.

j 6.- In' the manufacture of tin'plate, the steps ofsuccessively and uninterruptedly passing each plate into and through the flux,

the molten tin bath and the oil bath at one and. the same uniform, relatively high rate of speed and squeezing off surplus tin from the coated plate at a Sin le point and on the flux side. of the tin bath during the travel thereof through the tin bath. a

late the' e plates into and through the -flux into the molten tin bath at a substantially constant speed of not less 7. In the manufacture of tin plate, the 7 steps of successively and uninterruptedly' passing each plate into and through the flux,

the moltentin bath and the oil bath at the same uniform, relatively high rate of speed,

removing surplus tin from the coated plate at a single pomt and on the flux side of the tin bathduring'its travel through said tin bath and again removing surplus tinfrom .the coated plate during the passage thereof through said oil bath. J p

In testimony whereof I have hereunto set m hand.

y STEWART A. DAVIS. 

